Knowledge, interest, and motivations surrounding self-managed medication abortion among patients at three Texas clinics.

BACKGROUND: A rapid increase in restrictive abortion legislation in the United States has sparked renewed interest in self-managed abortion as a response to clinic access barriers. Yet little is known about knowledge of, interest in, and experiences of self-managed medication abortion among patients who obtain abortion care in a clinic. OBJECTIVES: We examined patients' knowledge of, interest in, and experience with self-managed medication abortion before presenting to the clinic. We characterized the clinic- and person-level factors associated with these measures. Finally, we examined the reasons why patients express an interest in or consider self-management before attending the clinic. MATERIALS AND METHODS: We surveyed 1502 abortion patients at 3 Texas clinics in McAllen, San Antonio, and Fort Worth. All individuals seeking abortion care who could complete the survey in English or Spanish were invited to participate in an anonymous survey conducted using iPads. The overall response rate was 90%. We examined the prevalence of 4 outcome variables, both overall and separately by site: (1) knowledge of self-managed medication abortion; (2) having considered self-managing using medications before attending the clinic; (3) interest in medication self-management as an alternative to accessing care at the clinic; and (4) having sought or tried any method of self-management before attending the clinic. We used binary logistic regression models to explore the clinic- and patient-level factors associated with these outcome variables. Finally, we analyzed the reasons reported by those who had considered medication self-management before attending the clinic, as well as the reasons reported by those who would be interested in medication self-management as an alternative to in-clinic care. RESULTS: Among all respondents, 30% knew about abortion medications available outside the clinic setting (37% in Fort Worth, 33% in McAllen, 19% in San Antonio, P < .001), and among those with prior knowledge, 28% had considered using this option before coming to the clinic (36% in McAllen, 25% in Fort Worth, 21% in San Antonio, P = .028). Among those without prior knowledge of self-management, 39% expressed interest in this option instead of coming to the clinic (54% in San Antonio, 30% in McAllen, 29% in Fort Worth, P < .001). Overall, 13% had sought out or tried any method of self-management before presenting to the clinic (16% in McAllen and 15% in Fort Worth vs 9% in San Antonio, P < .001). Experiencing barriers to clinic access was associated with having considered medication self-management (odds ratio, 2.2; 95% confidence interval, 1.7-3.0) and with seeking or trying any method of self-management before attending the clinic (odds ratio, 1.9; 95% confidence interval, 1.3-2.7). Difficulty affording the cost of in-clinic care was the most commonly cited reason for having considering medication self-management before attending the clinic. Reasons for interest in medication self-management as an alternative to clinic care included both access barriers and preferences for the privacy and comfort of home. CONCLUSION: Considering or attempting self-managed abortion may be part of the pathway to seeking in-clinic care, particularly among those experiencing access barriers. However, considerable interest in medication self-management as an alternative to the clinic also suggests a demand for more autonomous abortion care options.

Demand for Self-Managed Medication Abortion Through an Online Telemedicine Service in the United States.

Objectives. To examine demand for abortion medications through an online telemedicine service in the United States.Methods. We examined requests from US residents to the online telemedicine abortion service Women on Web (WoW) between October 15, 2017, and August 15, 2018. We calculated the population-adjusted rate of requests by state and examined the demographics, clinical characteristics, and motivations of those seeking services, comparing those in states with hostile versus supportive abortion policy climates.Results. Over 10 months, WoW received 6022 requests from US residents; 76% from hostile states. Mississippi had the highest rate of requests (24.9 per 100 000 women of reproductive age). In both hostile and supportive states, a majority (60%) reported a combination of barriers to clinic access and preferences for self-management. Cost was the most common barrier (71% in hostile states; 63% in supportive states; P < .001). Privacy was the most common preference (49% in both hostile and supportive states; P = .66).Conclusions. Demand for self-managed medication abortion through online telemedicine is prevalent in the United States. There is a public health justification to make these abortions as safe, effective, and supported as possible.

Hypertension and Acute Mountain Sickness in Himalayan Trekkers in Nepal: An Observational Cohort Study.

INTRODUCTION: A history of preexisting hypertension is common in people participating in mountain activities; however, the relationship between blood pressure (BP), preexisting hypertension, and acute mountain sickness (AMS) is not well studied. We sought to determine these relationships among trekkers in the Everest region of Nepal. METHODS: This was a prospective observational cohort study of a convenience sample of adult, nonpregnant volunteers trekking in the Everest Base Camp region in Nepal. We recorded Lake Louise Scores for AMS and measured BP at 2860 m, 3400 m, and 4300 m. The primary outcome was AMS. RESULTS: A total of 672 trekkers (including 60 with history of preexisting hypertension) were enrolled at 2860 m. We retained 529 at 3400 m and 363 at 4300 m. At 3400 m, 11% of participants had AMS, and 13% had AMS at 4300 m. We found no relationship between AMS and measured BP values (P>0.05), nor was there any relation of BP to AMS severity as measured by higher Lake Louise Scores (P>0.05). Preexisting hypertension (odds ratio [OR] 0.16; 95% CI 0.025-0.57), male sex (OR 0.59; 95% CI 0.37-0.96), and increased SpO2 (OR 0.93; 95% CI 0.87-0.98) were associated with reduced rates of AMS in multivariate analyses adjusting for known risk factors for AMS. CONCLUSIONS: AMS is common in trekkers in Nepal, even at 3400 m. There is no relationship between measured BP and AMS. However, a medical history of hypertension may be associated with a lower risk of AMS. More work is needed to confirm this novel finding.

Extreme event medicine: considerations for the organisation of out-of-hospital care during obstacle, adventure and endurance competitions.

Obstacle, adventure and endurance competitions in challenging or remote settings are increasing in popularity. A literature search indicates a dearth of evidence-based research on the organisation of medical care for wilderness competitions. The organisation of medical care for each event is best tailored to specific race components, participant characteristics, geography, risk assessments, legal requirements, and the availability of both local and outside resources. Considering the health risks and logistical complexities inherent in these events, there is a compelling need for guiding principles that bridge the fields of wilderness medicine and sports medicine in providing a framework for the organisation of medical care delivery during wilderness and remote obstacle, adventure and endurance competitions. This narrative review, authored by experts in wilderness and operational medicine, provides such a framework. The primary goal is to assist organisers and medical providers in planning for sporting events in which participants are in situations or locations that exceed the capacity of local emergency medical services resources.

Requests for Self-managed Medication Abortion Provided Using Online Telemedicine in 30 US States Before and After the Dobbs v Jackson Women's Health Organization Decision.

This study assesses changes in online telemedicine requests to self-manage abortions with medications before vs after the Dobbs v Jackson Women's Health Organization Supreme Court decision overturning Roe v Wade.

Prophylactic Acetaminophen or Ibuprofen Results in Equivalent Acute Mountain Sickness Incidence at High Altitude: A Prospective Randomized Trial.

OBJECTIVE: Recent trials have demonstrated the usefulness of ibuprofen in the prevention of acute mountain sickness (AMS), yet the proposed anti-inflammatory mechanism remains unconfirmed. Acetaminophen and ibuprofen were tested for AMS prevention. We hypothesized that a greater clinical effect would be seen from ibuprofen due to its anti-inflammatory effects compared with acetaminophen's mechanism of possible symptom reduction by predominantly mediating nociception in the brain. METHODS: A double-blind, randomized trial was conducted testing acetaminophen vs ibuprofen for the prevention of AMS. A total of 332 non-Nepali participants were recruited at Pheriche (4371 m) and Dingboche (4410 m) on the Everest Base Camp trek. The participants were randomized to either acetaminophen 1000 mg or ibuprofen 600 mg 3 times a day until they reached Lobuche (4940 m), where they were reassessed. The primary outcome was AMS incidence measured by the Lake Louise Questionnaire score. RESULTS: Data from 225 participants who met inclusion criteria were analyzed. Twenty-five participants (22.1%) in the acetaminophen group and 18 (16.1%) in the ibuprofen group developed AMS (P = .235). The combined AMS incidence was 19.1% (43 participants), 14 percentage points lower than the expected AMS incidence of untreated trekkers in prior studies at this location, suggesting that both interventions reduced the incidence of AMS. CONCLUSIONS: We found little evidence of any difference between acetaminophen and ibuprofen groups in AMS incidence. This suggests that AMS prevention may be multifactorial, affected by anti-inflammatory inhibition of the arachidonic-acid pathway as well as other analgesic mechanisms that mediate nociception. Additional study is needed.

The health equity implications of the Health Resources and Services Administration's Ryan White HIV/AIDS Program.

OBJECTIVE: Investigate the role of the Ryan White HIV/AIDS Program (RWHAP) - which funds services for vulnerable and historically disadvantaged populations with HIV - in reducing health inequities among people with HIV over a 10-year horizon. DESIGN: We use an agent-based microsimulation model to incorporate the complexity of the program and long-time horizon. METHODS: We use a composite measure (the Theil index) to evaluate the health equity implications of the RWHAP for each of four subgroups (based on race and ethnicity, age, gender, and HIV transmission category) and two outcomes (probability of being in care and treatment and probability of being virally suppressed). We compare results with the RWHAP fully funded versus a counterfactual scenario, in which the medical and support services funded by the RWHAP are not available. RESULTS: The model indicates the RWHAP will improve health equity across all demographic subgroups and outcomes over a 10-year horizon. In Year 10, the Theil index for race and ethnicity is 99% lower for both outcomes under the RWHAP compared to the non-RWHAP scenario; 71-93% lower across HIV transmission categories; 31-44% lower for age; and 73-75% lower for gender. CONCLUSION: Given the large number of people served by the RWHAP and our findings on its impact on equity, the RWHAP represents an important vehicle for achieving the health equity goals of the National HIV/AIDS Strategy (2022-2025) and the Ending the HIV Epidemic Initiative goal of reducing new infections by 90% by 2030.

Factors Associated With Knowledge and Experience of Self-managed Abortion Among Patients Seeking Care at 49 US Abortion Clinics.

Importance: Patients attending US abortion clinics may consider or try self-managing their abortion before coming to the clinic, yet little is known about the factors associated with self-management behavior. Objective: To examine the prevalence and factors associated with considering or attempting a self-managed abortion before attending a clinic. Design, Setting, and Participants: This survey study included patients obtaining an abortion at 49 independent, Planned Parenthood, and academic-affiliated clinics chosen to maximize diversity in geographic, state policy, and demographic context in 29 states between December 2018 and May 2020. Data were analyzed from December 2020 to July 2021. Exposures: Obtaining an abortion at a clinic. Main Outcomes and Measures: Knowledge of medications used to self-manage an abortion, having considered medication self-management before attending the clinic, having considered any method of self-management before attending the clinic, and having tried any method of self-management before attending the clinic. Results: The study included 19 830 patients, of which 99.6.% (17 823 patients) identified as female; 60.9% (11 834 patients) were aged 20 to 29 years; 29.6% (5824 patients) identified as Black, 19.3% (3799 patients) as Hispanic, and 36.0% (7095 patients) as non-Hispanic White; 44.1% (8252 patients) received social services; and 78.3% (15 197 patients) were 10 weeks pregnant or less. Approximately 1 in 3 (34%) knew about self-managed medication abortion, and among this subsample of 6750 patients, 1 in 6 (1079 patients [16.1%]) had considered using medications to self-manage before attending the clinic. Among the full sample, 1 in 8 (11.7%) considered self-managing using any method before clinic attendance, and among this subsample of 2328 patients, almost 1 in 3 (670 patients [28.8%]) attempted to do so. Preference for at-home abortion care was associated with considering medication self-management (odds ratio [OR], 3.52; 95% CI, 2.94-4.21), considering any method of self-management (OR, 2.80; 95% CI, 2.50-3.13), and attempting any method of self-management (OR, 1.37; 95% CI, 1.10-1.69). Experiencing clinic access barriers was also associated with considering medication self-management (OR, 1.98; 95% CI, 1.69-2.32) and considering any method of self-management (OR, 2.09; 95% CI, 1.89-2.32). Conclusions and Relevance: In this survey study, considering self-managed abortion was common before accessing in-clinic care, particularly among those on the margins of access or with a preference for at-home care. These findings suggest a need for expanded access to telemedicine and other decentralized abortion care models.

Factors Associated With Use of an Online Telemedicine Service to Access Self-managed Medical Abortion in the US.

Importance: People in the US have been seeking self-managed abortions outside the formal health care system using medications obtained through online telemedicine. However, little is known about this practice, including potential motivating factors. Objective: To examine individual reasons for accessing medication abortion through an online telemedicine service as well as associations between state- and county-level factors and the rate of requests. Design, Setting, and Participants: This population-based cross-sectional study examined all requests for self-managed medication abortion through an online consultation form available from Aid Access, a telemedicine service in the US, between March 20, 2018, and March 20, 2020. Main Outcomes and Measures: Individual-level reasons for accessing the telemedicine service were examined as well as the rate of requests per 100 000 women of reproductive age by state. Zip code data provided by individuals making requests were used to examine county-level factors hypothesized to be associated with increased demand for self-managed abortion: distance to a clinic (calculated using location data for US abortion clinics) and the population proportion identifying as a member of a racial/ethnic minority group, living below the federal poverty level, and having broadband internet access (calculated using census data). Results: During the 2-year study period, 57 506 individuals in 2458 counties in 50 states requested self-managed medication abortion; 52.1% were aged 20 to 29 years (mean [SD] age, 25.9 [6.7] years), 50.0% had children, and 99.9% were 10 weeks' pregnant or less. The most common reasons cited by individuals making requests were the inability to afford in-clinic care (73.5%), privacy (49.3%), and clinic distance (40.4%). States with the highest rate of requests were Louisiana (202.7 per 100 000 women) and Mississippi (199.9 per 100 000 women). At the county level, an increase of 1 SD (47 miles) in distance to the nearest clinic was significantly associated with a 41% increase in requests (incidence rate ratio, 1.41; 95% CI, 1.31-1.51; P < .001), and a 10% increase in the population living below the federal poverty level was significantly associated with a 20% increase in requests (incidence rate ratio, 1.20; 95% CI, 1.13-1.28; P < .001). Conclusions and Relevance: In this cross-sectional study, clinic access barriers were the most commonly cited reason for requesting self-managed medication abortion using an online telemedicine service. At the county level, distance to an abortion clinic and living below the federal poverty level were associated with a higher rate of requests. State and federal legislation could address these access barriers.

Demand for self-managed online telemedicine abortion in eight European countries during the COVID-19 pandemic: a regression discontinuity analysis.

OBJECTIVES: In most European countries, patients seeking medication abortion during the COVID-19 pandemic are still required to attend healthcare settings in person. We assessed whether demand for self-managed medication abortion provided by online telemedicine increased following the emergence of COVID-19. METHODS: We examined 3915 requests for self-managed abortion to online telemedicine service Women on Web (WoW) between 1 January 2019 and 1 June 2020. We used regression discontinuity to compare request rates in eight European countries before and after they implemented lockdown measures to slow COVID-19 transmission. We examined the prevalence of COVID-19 infection, the degree of government-provided economic support, the severity of lockdown travel restrictions and the medication abortion service provision model in countries with and without significant changes in requests. RESULTS: Five countries showed significant increases in requests to WoW, ranging from 28% in Northern Ireland (97 requests vs 75.8 expected requests, p=0.001) to 139% in Portugal (34 requests vs 14.2 expected requests, p<0.001). Two countries showed no significant change in requests, and one country, Great Britain, showed an 88% decrease in requests (1 request vs 8.1 expected requests, p<0.001). Among countries with significant increases in requests, abortion services are provided mainly in person in hospitals or abortion is unavailable and international travel was prohibited during lockdown. By contrast, Great Britain implemented a fully remote no-test telemedicine service. CONCLUSION: These marked changes in requests for self-managed medication abortion during the COVID-19 pandemic demonstrate demand for remote models of care, which could be fulfilled by expanding access to medication abortion by telemedicine.

Relative impact of pre-eclampsia on birth weight in a low resource setting: A prospective cohort study.

OBJECTIVES: Low birth-weight is a major risk factor for perinatal death in sub-Saharan Africa, but the relative contribution of determinants of birth-weight are difficult to disentangle in low resource settings. We sought to delineate the relationship between birth-weight and maternal pre-eclampsia across gestation in a low-resource obstetric setting. STUDY DESIGN: Prospective cohort study in a tertiary referral centre in urban Uganda, including 971 pre-eclampsia cases and 1461 control pregnancies between 28 and 42 weeks gestation. MAIN OUTCOME MEASURES: Nonlinear modeling of birth-weight versus maternal pre-eclampsia status across gestation. Models were adjusted for maternal-fetal characteristics including maternal age, parity, HIV status, and socio-economic status. Propensity score matching was used to control for the severity of pre-eclampsia at different gestational ages. RESULTS: Mean birth-weight for pre-eclampsia cases was 2.48 kg (±0.81SD) compared to 3.06 kg (±0.46SD) for controls (p < 0.001). At 28 weeks, the mean birth-weight difference between pre-eclampsia cases and controls was 0.58 kg (p < 0.05), narrowing to 0.17 kg at 39 weeks (p < 0.01). Controlling for pre-eclampsia severity only partially explained this gestational difference in mean birth-weight between pre-eclampsia cases and controls. Holding gestational age constant, pre-eclampsia status predicted 7.1-10.5% of total variation in birth-weight, compared to 0.05-0.7% for all other maternal-fetal characteristics combined. CONCLUSIONS: Pre-eclampsia is the dominant predictor of birth-weight in low-resource settings and hence likely to heavily influence perinatal survival. The impact of pre-eclampsia on birth-weight is smaller with advancing gestational age, a difference that is not fully explained by controlling for pre-eclampsia severity.

Ambulatory Blood Pressure at Sea Level and High Altitude in a Climber with a Kidney Transplant and Hypertension.

Background and Objectives: High altitude may increase blood pressure (BP) and the kidney plays an important role in acclimatization. Little is known about how transplanted kidneys respond to the hypoxic stress at high altitude. We compared 24 hour ambulatory BP in a climber with a kidney transplant and hypertension at sea level and at high altitude (2860-4300 m). Methods: Welch-Allyn ABPM 6100 monitor was used to collect heart rate, systolic BP (SBP), and diastolic BP every 30 minutes while awake, and hourly while asleep. BP was monitored for 49 hours at sea level and for 53 hours at 2860-4300 m. Results: Overall mean SBP did not differ between altitudes. At high altitude, the participant's mean nocturnal BP increased, but this "reverse dipping" pattern was not observed at sea level. The participant had no evidence of altitude illness or infectious complications at high altitude. Conclusions: This case builds on previous reports that kidney transplant recipients may safely travel to high altitude. Further study is required to determine the generalizability to other travelers with kidney transplant and/or underlying hypertension, and the clinical significance of short-term elevated nocturnal BP at high altitude.

Advance Provision of Mifepristone and Misoprostol via Online Telemedicine in the US.

This cross-sectional study examines trends in the demand and characteristics and motivations of individuals who requested advance provision of abortion medications.

Simultaneous Compared With Interval Medical Abortion Regimens Where Home Use Is Restricted.

OBJECTIVE: To evaluate outcomes with simultaneous administration of mifepristone and misoprostol for medical abortion at 63 days of gestation or less in the year after its implementation in a British clinic system. METHODS: We conducted a retrospective cohort study using deidentified data from the electronic booking and complications databases and medical records of women who underwent medical abortion at British Pregnancy Advisory Service. Our primary outcome was treatment success with simultaneous dosing compared with a regimen with a 24- to 48-hour interval between medications. We defined success as complete abortion without surgical evacuation and without continuing pregnancy. To assess relative regimen effectiveness while accounting for self-assignment to simultaneous or interval dosing, we modeled the probability of treatment success using logistic regression with propensity score adjustment for demographic and clinical characteristics. Secondary outcomes were reasons for abortion failure and clinically significant adverse events (hospital admission, blood transfusion, intravenous antibiotic administration). RESULTS: Of 28,901 women treated between May 2015 and April 2016, 85% chose simultaneous dosing. Overall success rates were high with both regimens but lower with simultaneous than with interval dosing (94.5% vs 97.1%, respectively, adjusted relative risk 0.973, 95% CI 0.967-0.979). For both regimens, success rates were lower at higher gestational ages, but the relative effectiveness of simultaneous dosing did not vary significantly with gestational age (P=.268). Surgical intervention rates for continuing pregnancy were lowest at 49 days of gestation or less (1.4% simultaneous vs 0.2% interval, P<.001) and highest at 57-63 days of gestation (5.0% and 2.2%, P<.001). The rate of clinically significant adverse events was 0.2% and did not differ by regimen (P=.972). CONCLUSION: Simultaneous administration of mifepristone and misoprostol is 97% as effective as a 24- to 48-hour interval at all gestational ages 63 days or less with no increase in the risk of clinically significant adverse events. Pragmatic use of simultaneous dosing is reasonable given the small difference in effectiveness.

Blood Pressure and Altitude: An Observational Cohort Study of Hypertensive and Nonhypertensive Himalayan Trekkers in Nepal.

Keyes, Linda E., Thomas Douglas Sallade, Charles Duke, Jennifer Starling, Alison Sheets, Sushil Pant, David S. Young, David Twillman, Nirajan Regmi, Benoit Phelan, Purshotam Paudel, Matthew McElwee, Luke Mather, Devlin Cole, Theodore McConnell, and Buddha Basnyat. Blood pressure and altitude: an observational cohort study of hypertensive and nonhypertensive Himalayan trekkers in Nepal. High Alt Med Biol. 18:267-277, 2017. OBJECTIVES: To determine how blood pressure (BP) changes with altitude in normotensive versus hypertensive trekkers. Secondary aims were to evaluate the prevalence of severe hypertension (BP ≥180/100 mmHg) and efficacy of different antihypertensive agents at high altitude. METHODS: This was an observational cohort study of resting and 24-hour ambulatory BP in normotensive and hypertensive trekkers at 2860, 3400, and 4300 m in Nepal. RESULTS: We enrolled 672 trekkers age 18 years and older, 60 with a prior diagnosis of hypertension. Mean systolic and diastolic BP did not change between altitudes in normotensive or hypertensive trekkers, but was higher in those with hypertension. However, there was large interindividual variability. At 3400 m, the majority (60%, n = 284) of normotensive participants had a BP within 10 mmHg of their BP at 2860 m, while 21% (n = 102) increased and 19% (n = 91) decreased. The pattern was similar between 3400 and 4300 m (64% [n = 202] no change, 21% [n = 65] increased, 15% [n = 46] decreased). BP decreased in a greater proportion of hypertensive trekkers versus normotensives (36% [n = 15] vs. 21% at 3400 m, p = 0.01 and 30% [n = 7] vs. 15% at 4300 m, p = 0.05). Severe hypertension occurred in both groups, but was asymptomatic. In a small subset of participants, 24-hour ambulatory BP monitoring showed that nocturnal BP decreased in normotensive (n = 4) and increased in hypertensive trekkers (n = 4). CONCLUSIONS: Most travelers, including those with well-controlled hypertension, can be reassured that their BP will remain relatively stable at high altitude. Although extremely elevated BP may be observed at high altitude in normotensive and hypertensive people, it is unlikely to be symptomatic. The ideal antihypertensive regimen at high altitude remains unclear.

Older age, chronic medical conditions and polypharmacy in Himalayan trekkers in Nepal: an epidemiologic survey and case series.

BACKGROUND: The number of tourists in Nepal doubled between 2003 and 2013 is nearly 800 000. With the increased popularity of trekking, the number of those with pre-existing medical conditions requiring access to healthcare is likely to increase. We therefore sought to characterize the demographics and health status of trekkers on the Everest Base Camp route in the Solukhumbu Valley. In addition, we report cases that illustrate the potential complications of an ageing and medicated population of trekkers with underlying diseases. METHODS: Trekkers over 18 years were enrolled in a larger observational cohort study on blood pressure at high altitude at 2860 m. They answered a questionnaire regarding demographics, medical history and current medications. Acute medical problems relating to medication use that were brought to the attention of investigators were documented and are presented as case reports. RESULTS: We enrolled 670 trekkers, 394 (59%) male, with a mean age of 48 years (range 18-76). Pre-existing medical conditions were reported by 223 participants (33%). The most frequent conditions included hypertension, hypercholesterolemia, migraines and thyroid dysfunction. A total of 276 participants (41%) reported taking one or more medications. The most common medications were acetazolamide (79, 12%), antihypertensives (50, 8%) and NSAIDs (47, 7%), with 30 classes of drugs represented. Excluding acetazolamide, older trekkers (age >50 years) were more likely than younger ones to take medications (OR = 2.17; 95% CI 1.57-3.00; P <0.05). Acetazolamide use was not related to age. CONCLUSIONS: Our findings illustrate a wide variety of medical conditions present in trekkers in Nepal with wide-ranging potential complications that could pose difficulties in areas where medical care is scarce and evacuation difficult. Our cases illustrate the potential problems polypharmacy poses in trekkers, and the need for local and expedition healthcare workers to be aware of, and prepared for the common medical conditions present.

Infectious Diseases at High Altitude.

Travel to elevations above 2,500 m is an increasingly common activity undertaken by a diverse population of individuals. These may be trekkers, climbers, miners in high-altitude sites in South America, and more recently, soldiers deployed for high-altitude duty in remote areas of the world. What is also being increasingly recognized is the plight of the millions of pilgrims, many with comorbidities, who annually ascend to high-altitude sacred areas. There are also 400 million people who reside permanently in high mountain ranges, which cover one-fifth of the Earth's surface. Many of these high-altitude areas are in developing countries, for example, the Himalayan range in South Asia. Although high-altitude areas may not harbor any specific infectious disease agents, it is important to know about the pathogens encountered in the mountains to be better able to help both the ill sojourner and the native high-altitude dweller. Often the same pathogens prevalent in the surrounding lowlands are found at high altitude, but various factors such as immunomodulation, hypoxia, poor physiological adaptation, and harsh environmental stressors at high altitude may enhance susceptibility to these pathogens. Against this background, various gastrointestinal, respiratory, dermatological, neurological, and other infections encountered at high altitude are discussed.